Removable verticle media insert system for air treatment

ABSTRACT

A support framework for containing a granular medium that is used to remediate corrosive vaporous pollutants in an air stream. The support framework is situated within a plenum and comprises two concentric open-lattice weave cylinders made from corrosion resistant fiberglass reinforced plastic (FRP). The cylinders are of differing diameters and the granular medium is placed into and contained within the open space formed between the inside wall of the outer cylinder and the outside wall of the inner cylinder. The open-lattice weave design allows a greater radial flow through the medium per unit of time, doing so with less pressure drop and using less energy than the prior art. The use of FRP to form the cylinder walls allows creation of large units that are suitable for use in municipal and industrial settings, which was not possible previously.

BACKGROUND OF THE INVENTION

1. Field of Invention

The invention relates to an apparatus and process for treating airstreams to remove pollutants. More particularly it relates to the use ofopen weave fiberglass reinforced plastic (“FRP”) to create a concentricframework within a plenum containing a porous granular media whichfacilitates interactions which capture pollutants from an air streambeing moved horizontally and radially through the media either inwardlyor outwardly.

2. Description of the Relevant Prior Art

Vaporous pollutants, which are frequently toxic or corrosive or both,are created in a multiplicity of municipal, commercial and agriculturalprocesses and become part of output airstreams. Treatment of theseoutput airstreams to strip out the pollutants is important to humanhealth, to prevent damage to equipment, to protect the environment andto provide odor control.

Typical treatment of airstreams is to pass the stream through a reactivemedia in a containment structure within a plenum which serves as areactor. Issues include plenum size, choice of material and energyconsumption. In instances where the air stream contains corrosive gases,the materials used to form the containment structure are chosen to be asnon-reactive as practical. This need has traditionally placed alimitation upon the size of media containment structures. Used alone asinert structural materials, plastics do not have the structural strengthfor creating large structures. Metals have the strength but corrode tooeasily.

Over time, two differing reactor designs have emerged. The earlierreactors used vertical flow of the air stream under pressure or vacuum,thus requiring a considerable consumption of energy in their operation.

On the other hand, radial flow reactors work at ambient or just aboveambient pressures, requiring no compressors or vacuum units or expensiveseals for their operation and presenting less potential for escape ofuntreated air into the environment.

In general, radial air-flow reactors consist of a containment vessel (aplenum) within which is located a series of baffles that separate theincoming polluted air from the exiting purified air. The space betweenthe baffles holds and supports the remediation media. Commonly, thebaffles consist of a pair of cylindrically shaped elements, one having asmaller diameter than the other and being concentrically located withinthe former. These cylinder walls have pore spaces through which the airpasses. In an inward flow reactor, the air stream moves from an inletmanifold through the outer baffle into the remediation medium, and thenthrough the inner baffle and into an exit manifold. Or the reactor canbe designed to have a reversed flow direction described as an outwardflow reactor.

Past radial flow reactor designs suffered from some problems of theirown. One of the main problems being that the structural weakness ofnon-reactive media containment materials prevented the creation of unitslarge enough to efficiently handle large volumes of pollutants.Increasing the bulk of the solid portion of the containment cylinders tomake the walls stronger reduced the amount of open air flow space withinthe cylinder walls, thus decreasing the efficiency of and increasing thecost of operating the unit.

Statement of the Objectives

Accordingly, it is an objective of this invention to provide a corrosionresistant media support system for use in a radial flow reactor, saidsupport system having the structural strength allowing for its use inlarge commercial and municipal reactors, yet also having a flexibilityof design allowing for use in small sized reactors, and at the same timeproviding media containment support walls with a lower solid to throughspace ratio that allows for the remediation of a greater volume of airper unit of time relative to other comparably sized units and doing sowith a low pressure drop from the inlet side to the outlet side of themedia containment structure, thus simplifying installation andconserving energy.

Another object of the invention is to provide a containment structurethat is equally suitable for use with a variety of media, includingporous granular substrate media such as activated carbon, or media suchas foam and reticulated foam Another object of this invention is toprovide a containment structure design that allows creation of supportsthat can be retrofitted into existing reactors.

Other objectives, advantages and novel features of the invention willbecome apparent to those skilled in the art upon examination of theinvention and the accompanying drawings.

SUMMARY OF THE INVENTION

The invention involves the creation of two corrosion resistantfiberglass-reinforced plastic (FRP) cylinders of differing diametersthat have been extruded in a woven pattern with approximately a 68%through space ratio; the walls of each of which cylinders comprise athree layered construction that is fused into a unit, the layers being:an external FRP wall, a central corrosion resistant screen material andfinally an internal FRP wall that matches the configuration of and isarranged colinear with the open weave pattern of the outer FRP segmentof the wall. The cylinders are concentrically situated one within theother within a vertically standing plenum, the space between the twocylinders being designed to hold a medium capable of remediating toxic,corrosive vapors that are carried to it in an air stream that movesthrough the purification system in a radial flow direction.

BRIEF DESCRIPTION OF THE DRAWINGS

Further objectives and advantages of the invention will be apparent fromthe following detailed description when taken in conjunction with theaccompanying drawings illustrating a preferred embodiment pf theinvention. The drawings are:

FIG. 1 a. Presents a cross sectional view looking down onto the top of amedia support cylinder.

FIG. 1 b. Presents a diagrammatic side view of a section of a mediasupport cylinder wall.

FIG. 2. Presents a perspective view as a vertical cross section at thevertical axis center of a radial-flow air remediation system plenum.

FIG. 3. Presents a sectional perspective view at the top of the bodysection of a remediation system plenum with the removable split-coversection removed over one half of the unit.

FIG. 4. Presents a lateral view of the inter-connected attachment of theremovable split-cover sections of the plenum's top cover as well as therelationship of the removable split-cover section to the base section ofthe plenum.

FIG. 5. Presents a view of a portion of the media containment section ofa large radial flow vaporous pollutant remediation plenum depicting alaborer retrofitting a probe for an air quality monitoring devicethrough to the inside of the external FRP lattice wall of the mediasupport system and into the media containment space.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

The invention involves the creation of two open weave walled cylindersof different diameters that are made of corrosion resistantfiberglass-reinforced plastic (FRP) or other corrosion resistantmaterial and that are situated one within the other within a verticallystanding plenum serving as a radial flow air purification reactor.

Viewed from above in FIG. 1 a, the cylinder walls consist of a sandwichof three layers that are fused into a singular element during theirfabrication: an external layer of corrosion resistant FRP 1 FIG. 1 a, acentral screen material layer 2 FIG. 1 a, and an internal layer ofcorrosion resistant FRP 3 FIG. 1 a.

Seen in a sectional side view, each continuous basket weave FRP cylinderdisplays an outer layer of FRP created in a diamond shape pattern 1 FIG.1 b with the middle layer screen material of the cylinder wall 2 FIG. 1b filling the open spaces left within the diamond shaped open spaces ofthe outer cylinder wall layer 1; said screen material 2 having a poresize slightly smaller than the size of the units of the purificationmedia that is to be contained. The central most FRP layer of the wall isnot visible, being of the same design and created to lie in alignmentwith the outer FRP layer 1 FIG. 1 b but being situated internal to thescreen layer 2.

The wall elements, when viewed from the side as in FIG. 1 b, present asa fused panel in which the central-core section 2 is a corrosionresistant screen having an approximate pore space to solid materialratio of 50%; the superimposed internal and external support framelayers 1 are solid and present no pore space within their lattice workwalls, and represent approximately 32 percent of the total cylindricalwall area; the total configuration creating an excellent pore space tosolid support ratio of approximately 30-34% of the support cylinder'swall area while creating an exceptional structural strength of thecylinder walls.

When viewing a perspective view as a vertical cross section at thelongitudinal center of an air remediation plenum FIG. 2; the mediacontainment space 4 FIG. 2, is bounded externally by the lateral FRPcylinder wall 3 and centrally by the inner FRP cylinder wall 5; space 4being designed to contain media capable of remediating toxic, corrosivevapors that are carried to it in an air stream that moves through thepurification system in a radial flow direction. The cylindrical supportwalls 3 & 5 FIG. 2 are aligned coaxially with the vertically standingexternal wall of the plenum 7 a, and provide for a uniform thickness ofremediation medium in a radial direction between the inlet-manifold side2 and the outlet-manifold side 6 of the plenum over the entire length ofthe cylindrical media bed 4.

The granular porous substrate material held within the cylinders 3 & 5FIG. 2, commonly activated charcoal, but not limited to being activatedcharcoal, is commonly 3-4 mm in diameter, but could be larger or smallerdependent upon the needs of the particular application.

By presenting a perspective view as a vertical cross section at thevertical axis center of a radial-flow air remediation system plenum as apreferred embodiment of a complete radial flow air purification unit,FIG. 2 presents an example from which can be learned one method ofaligning and supporting the FRP media support walls that are thefoundation of this invention. This example is not intended to representnor should it be taken to be the sole manner of appropriately aligningand supporting the FRP cylinders, rather, it is presented to educatepeople familiar with the art as to a method of fabricating a plenum suchthat there is ease of introduction and removal of the FRP cylinders intothe plenum as needed, and such that control of the air stream pathwaythroughout the plenum presents minimal possibility of the escape ofunremediated air into the environment while providing maximal flow ofthe airstream from the inlet to the outlet side of the plenum with aminimal pressure drop between the inlet and the outlet sides of theunit.

The plenum FIG. 2 that contains cylinders 3 & 5 FIG. 2 comprises a basesection 7abcdefg, and a removable top section 9-14. Unremediated airenters the plenum through the air intake pipe 1 FIG. 2, and enters aninlet manifold 2, the lateral wall of which inlet manifold 2 is formedby the inner aspect of the side wall 7 a of the plenum. The unremediatedair then flows horizontally through the lateral FRP support cylinderwall 3 FIG. 2, then continues radially through the media bed section 4,next passing through the internal most FRP support cylinder wall 5, andinto the outlet manifold 6 after which it exits as remediated air.

For use within a radial flow remediation plenum designed to allowremoval of the media support as a unitary segment for purposes of mediareplacement, the bases of the FRP cylinders are joined, forming a basketshape, however, in the present embodiment, the FRP cylinders 3 & 5 FIG.2 are not removed during the process of replacing spent remediationmedia and so are not conjoined at the base. In the present embodiment,two concentric, circular positioning sections 7 c & 7 d FIG. 2 areformed by projections upwards from the floor 7 b of the plenum.Projection 7 c FIG. 2 has an internal diameter slightly larger than thatof the external diameter of the lateral FRP support cylinder wall 3, andserves to position the base of that cylinder and to prevent lateralspread of the base of that cylinder under the weight of the mediaparticles in the media bed section 4. Projection 7 d FIG. 2 has anexternal diameter that is slightly smaller than the internal diameter ofthe central most FRP support tube wall 5, and serves to position thebase of that cylinder and to prevent displacement of the base of thatcylinder in towards the outlet manifold 6 under the weight of the mediaparticles located in the media bed section 4.

The circular floor section 7 b FIG. 2 that forms the bottom seal sectionof the plenum, is appropriately anchored by one of several means to anappropriate foundation section, and at its periphery is joined to theside wall 7 a of the plenum, which side wall forms the lateral boundaryof the inlet manifold 2. Above, said side wall 7 a FIG. 2 is continuouswith the vertical collar 7 efg portion of the plenum's base section 7abcdefg. Said collar 7 efg FIG. 2 forms a constriction at the top ofsaid side wall 7 a section in which section 7 e of said collar 7 efg isseen as an inward projection at 90° to the side wall 7 a, and then turns90° upwards as the vertical section seen at 7 f; said vertical section 7f then reflects laterally at 90° to form the laterally projecting flange7 g that serves as the top plate of the base section 7 abcdefg of theplenum.

The configuration of collar 7 efg FIG. 2 specifically provides: ahorizontal projection 7 e FIG. 2 that forms the top sealing elementcovering the intake manifold 2; a vertical portion 7 f that serves asthe top guide/support for positioning the external FRP cylinder 3; and alaterally projecting horizontal flange 7 g that is perforated by holes(not visible) designed to receive bolts/nuts 10 that serve to attach theplenum's base section 7 abcdefg to the removable split cover section 9.It will be noted that a gasket 8 FIG. 2 is interposed between flange 7 gand the removable split-cover 9 section of the plenum and serves to sealthe junction of the two parts. A circular, central cutout in removablesplit-cover section 9 FIG. 2 represented by line cl serves as the topguide/support for positioning the internal FRP cylinder 5 and keeps thetop of said cylinder properly aligned such that it forms the peripheralboundary of the exit manifold 6 within the base section 7 abcdefg of theplenum. Removable split-cover section 9 FIG. 2, has 2 sets of holes, aperipheral set designed to receive bolts/nuts 10, and a seriessurrounding the central cutout that receive bolts/nuts 12 whichbolts/nuts affix said split-cover section to a surmounting cover sectioncollar 13 abc.

As will be seen in FIGS. 3 and 4, removable split-cover section 9 isactually formed by the combination of two mirror image sections, thedetails of which configuration is not presented here for sake ofclarity. A series of transverse braces (not shown but described asinternal cross braces 15 a & 15 b in FIG. 3, affix the top portion ofthe central most FRP support cylinder wall 5 FIG. 2 to the verticalsection 7 f of the base section vertical collar 7 efg and preventdistortion of said support cylinder wall in towards the outlet manifold6 under the weight of the media in the media bed section 4.

Cover section collar 13 abc FIG. 2 is formed of an inferior,horizontally aligned flange 13 a through which the bolts 12 pass inorder to attach said collar to top section 9. At its centraltermination, flange 13 a FIG. 2 then turns upwards at 90° as section 13b which then is continuous with the 90° laterally projecting flangesection 13 c. Said flange section 13 c FIG. 2 being pierced by holes 14to receive bolts (not shown) for attachment to an exit duct that carriesthe remediated air into the environment.

Lines a¹ and a² FIG. 2 represent the internally projecting curvature ofthe internal aspect of the side wall 7 a of the plenum. Lines b¹ and b²FIG. 2 represent the internally curved projections of the internalaspect of the lateral FRP support cylinder wall 3. Lines c¹ and c² FIG.2 represent the top cross section of the central most FRP supportcylinder 5.

Greater detail of the connection of and sealing of the base section 7abcdefg FIG. 2 to the top section 9-14 FIG. 2 of the plenum is presentedas a sectional perspective view looking down at the top of the unit inFIG. 3. In FIG. 3 it is seen that a portion of the split-cover section 9FIG. 3 has been removed over the forward half of the plenum. The topmostportion 7 fg FIGS. 2 & 3 of the base section vertical collar 7 efg FIGS.2 & 3 is shown in the lower left corner of the diagram. The top flange 7g FIG. 3 of that section of the plenum is covered by a gasket 8 withholes 8 a to receive bolts 10 (not shown) that affix the removablesplit-cover section 9 to the top flange 7 g of the base section of theplenum 7 abcdefg FIG. 2.

An internal cross brace 15 a FIG. 3 joins the top portion of the centralmost FRP support cylinder wall 5 FIG. 2 to the vertical section 7 f FIG.3 of the base section vertical collar 7 efg. A portion of another of thefour such internal cross braces is seen as 15 b FIG. 3 around at theleft rear of the drawing. Said cross braces prevent distortion of thecentral most support cylinder wall in towards the outlet manifold 6 FIG.2 under the weight of the media in the media bed section 4; the lateralattachment of Internal supports 15 a & 15 b FIG. 3 to base sectionvertical collar section 7 f FIG. 3 are via T shaped projections thatattach to the walls of the base section of the plenum with bolts 15 cFIG. 3, only two of which are seen, the others not being visible in thisdrawing.

Gasket 11 FIG. 3 with holes 1 la is seen near the center of the plenum.This gasket serves to separate and form the airtight seal between theremovable split-cover section 9 FIG. 3 and the cover section collar 13abc (not shown here but depicted in FIG. 2). It should be noted that theportion of the outlet manifold 6 FIG. 3 that is found above removablesplit-cover section 9 FIG. 3 is actually formed by the internal aspectof the cover section collar 13 abc FIG. 2 which cover section collar hasbeen deleted in FIG. 3 in order to allow visualization of gasket 11 andinternal cross braces 15 a, 15 b. Thus, the area demarcated as theoutlet manifold 6 in FIG. 3 represents the potential space that existsonly when said cover section collar is actually affixed to the basesection of the plenum (as shown prior in FIG. 2). Numbers 9 a ¹ and 9 a² FIG. 3, seen as the topmost elements and located at the left of outletmanifold 6, are the vertical connecting elements that hold the twosections of the removable split-cover section 9 together with bolts (notshown) that are placed through holes shown as 9 a & 9 b; said verticalconnecting elements being continuous with and projecting upward at a 90°angle across the intersecting widths of the two halves of the removablesplit-cover section 9. A gasket that forms the sealing element betweenthese two vertical connecting elements is not shown, but arepresentation of same is found in FIG. 4.

FIG. 4 presents a diagrammatic lateral view representation of thevertical interconnecting elements 9 a ¹ and 9 b ¹ FIG. 4 of theremovable split-cover sections 9 a and 9 b. The bases of said verticalconnecting elements are welded to the removable top split-cover sections9 a and 9 b FIG. 4 across their widths, and where verticalinterconnecting elements 9 a ¹ and 9 b ¹ come together they areinterconnected by bolts 9 c (only one of which is visible). The line 9 dFIG. 4 represents a vertically situated gasket that seals the junctionbetween the attachment flanges 9 a ¹ and 9 a ².

Bolts 10 FIG. 4 serve as the connection of the removable split-coversections 9 a and 9 b to the top flange section 7 g of the base sectionvertical collar 7 efg. The gasket situated between the removablesplit-cover sections 9 a/9 b FIG. 4 and top flange section 7 g of basesection vertical collar 7 efg, is represented by the dark line at 11.The relative position of the above described elements to the walls ofthe base section of the plenum is indicated by lines 7 aefg FIG. 4. Thebracketed section 13 abc FIG. 4 has been included in order to spatiallyindicate the relationship of the removable split-cover sections 9 a & 9b to the cover section collar 13 abc that forms the continuation of theoutlet manifold above the level of the removable split-cover sections 9^(a) and 9 ^(b).

The great strength and design flexibility created by this inventionallow of creation of FRP cylinders for plenums ranging from very smallto large to commercial/industrial size radial flow units. Currentproduction has created units ranging from small units in which the FRPsupport cylinders were 4 feet tall, having an inner FRP tube internaldiameter of 6 inches with the external tube diameter being 3 feet; up toa very large unit, 20 feet tall with an internal FRP tube diameter of 7feet and an external FRP tube diameter of 11 feet. With respect to thelarger construction mentioned above, it is the specific combination ofmaterials and design elements created in this invention that allows ofthe creation of systems suitable for service in large scale industrialand commercial purification projects, such as were not possibleutilizing the prior art. As an illustration of the actual size of such aconstruction, FIG. 5 presents a perspective drawing showing a man 1 FIG.5 braced in a horizontal position between the central most FRP supportcylinder wall 5 and the lateral FRP support cylinder wall 3.Significantly, the strength of the two FRP cylinder walls 3 & 5 FIG. 5is such that the man is able to support his weight by applying pressureagainst said walls while he is preparing a hole for the placement of anaccessory entry port for placement of a test probe through the lateralFRP support tube wall 3 into media bed section 4. The drawing is notintended to display any new feature of the invention, rather, it isintended to show the large scale of remediation units that can befabricated using this invention, the size of which was not possibleprior to this invention.

1. A media support wall framework comprising three layers of materialthat are fused into a single sheet;
 1. an external layer of corrosionresistant Fiberglass Reinforced Plastic (FRP) that is created in theform of an open-weave diamond shaped lattice having a 65% to 75% ratioof through space between the bands of FRP material,
 2. a central layerof corrosion resistant plastic screening material having a pore sizecomprising between 40% and 60% of said screen's total surface with saidpores being slightly smaller than the granule size of the medium it isto be used to contain, and,
 3. an internal layer designed and made ofthe same material and in the same pattern as the external layer andplaced so as to be in alignment with the external latticework as closelyas possible throughout the full vertical length of the cylinder wall,said framework being formed into an appropriate shape and a variety ofsizes for the containment of granular organic porous remediation mediasuitable for treating contaminated air, including but not necessarilybeing limited to air containing corrosive vapors.
 2. The media supportwall of claim 1 in which the combined open pore space of the screenmaterial and the FRP framework ranges from 25% to 35% of the totalsurface area of the support wall area.
 3. The media support wallframework of claim 1 in which said framework is situated within a plenumhaving an air inlet, an air outlet, bottom, top and either multifacetedor cylindrical sidewall(s), and which plenum is formed having anappropriately anchored base section, and a removable split-top section,and within which are situated two separate, concentrically arrangedmedia support cylinders of different diameters; said cylinders beingaligned vertically coaxial with and extending from the top to the bottomof the solid, outer wall of the base section of the plenum, thusforming, between themselves, a space allowing of a uniform thickness ofremediation media in a radial direction between the inlet manifold andoutlet manifold of the plenum over the entire vertical length of thecylinders; the walls of said cylinders being of a proportionate size andthickness for use within plenums of greater or lesser size as the needmay vary; and in which the cylindrical media support walls have anoverall through space to solid surface ratio of between 28% and 34% forallowing passage of contaminated air from the inlet manifold, throughthe lateral support cylinder wall, into and through the remediationmedia, then through the central most support cylinder wall, and finallyinto an outlet manifold for discharge from the unit; said cylinder'swalls being held at their proportionate distance from each otherthroughout their vertical lengths by their situation into preparedreceptacles in the bottom plate of the base section of the plenum aswell as by their situation within support collars at the top of the basesection of said plenum, with optional cross braces serving as furthersupport at the top of the cylinders in larger units; thus forming amedia support system that is designed such that the support cylindersare not commonly removed during the process of removing and replacingspent remediation media particles.
 4. The media support wall frameworkof claim 3 in which the bases of the two cylinders are conjoined by asolid FRP floor section, said cylinders being held at theirproportionate distance from each other throughout their vertical lengthsby said floor section in conjunction with their situation within supportcollars at the top of the base section of said plenum, with optionalcross braces serving as further support at the top of the cylinders inlarger units; thus forming a media support system in which the supportcylinders are designed to be removed as a unit for purposes of removingand replacing spent remediation media particles.
 5. The media supportcylinders of claim 1 wherein the configuration of the FRP cylinders isdesigned to support a remediation medium other than a porous organicgranular substrate media, the basket weave walls of the supportcylinders being designed to support inorganic media such as conventionalfoam, reticulated foam, etc., or organic media such as lava rock, woodchips, etc.
 6. The media support cylinders of claim 5 wherein the screensections of the FRP cylinders have a pore space sized slightly smallerthan the diameter of the specific organic media being used, such as lavarock or wood chips.
 7. The media support cylinders of claim 5 whereinthe FRP cylinders are not formed with a central screen membrane,comprising only basket weave walls made of FRP, said cylinders beingdesigned specifically for the support of non-granular, inorganic mediasuch as conventional foam or reticulated foam.
 8. The media supportcylinders of claim 1 wherein the basket weave walls of the supportcylinders are formed of non-FRP plastic or other such materials that arecorrosion resistant.
 9. The media support cylinders of claim 8 whereinthe basket weave walls of the support cylinders are designed to supportremediation media other than a porous organic granular substrate medium,such cylinder wall configurations being designed to support inorganicmedia such as conventional foam or reticulated foam, or, organic mediasuch as lava rock or wood chips.
 10. The media support cylinders ofclaim 9 wherein the screen sections of the support cylinder wall have apore space sized slightly smaller than the diameter of the specificorganic media, such as lava rock or wood chips.
 11. The media supportcylinders of claim 9 wherein the support cylinder walls are not linedwith screen material, said cylinder walls being designed specificallyfor the support of non-granular, inorganic media such as conventionalfoam or reticulated foam.
 12. The media support cylinders of claim 8 inwhich the two support cylinders are joined together at the base for usein remediation reactor containment vessels that allow removal of themedium support system as a unit for purposes of recharging the unit withfresh remediation media.
 13. The media support cylinders of claim 3 inwhich the two support cylinders are joined by cross braces at the lowestand topmost levels, said cross braces serving to maintain the desiredseparation between the internal aspect of the external cylinder and theexternal aspect of the internal cylinder, and, which cylinders also bearexternal, horizontally extending braces sized to situate and stabilizethe cylinders against the internal aspect of the side walls of plenumsthat were not originally designed to receive said support cylinders. 14.The media support cylinders of claim 8 in which the two supportcylinders are joined by cross braces at the lowest and topmost levels,said cross braces serving to maintain the desired separation between theinternal aspect of the external cylinder and the external aspect of theinternal cylinder, and, which cylinders also bear external, horizontallyextending braces sized to situate and stabilize the cylinders againstthe internal aspect of the side walls of plenums that were notoriginally designed to receive said support cylinders.
 15. A process fortreating contaminated air: a. by moving the contaminated air, at ambientor slightly above ambient air pressure, into the inlet manifold of aplenum then radially through a medium comprising a granular poroussubstrate media such as activated charcoal, or other organic media suchas wood chips or lava rock; b. contacting the air with media containedwithin two concentrically arranged support cylinders of differingdiameters, said cylinders having porous walls, and said walls comprisinga fused sandwich formed from a single layer of corrosion resistantplastic screening situated between two layers of woven bands ofFiberglass Reinforced Plastic (FRP), the lattice weave FRP wall segmentof said walls being formed in a diamond shaped basket weave arrangement,the total through space of such combined screen and FRP wall materialscomprising between 25% and 45% of the total wall area of said cylinders;c. after passing through which media and cylinders the now purified airis moved into an outlet manifold; d. and thence exits from the plenum.16. A process for treating contaminated air: a. by moving the air, atambient or slightly above ambient air pressure into the inlet manifoldof a plenum then radially through an inorganic medium such as, foam orreticulated foam; b. containing said medium between two concentricallyarranged support cylinders of differing diameters, said cylinders beingformed of a corrosion resistant material such as plastic or other likematerials, and having porous walls by virtue of being formed in adiamond shaped basket weave arrangement, the total through space ofwhich support wall material comprises between 65% and 75% of the totalwall area of said cylinders c after passing through which media andcylinders, the now purified air is moved into an outlet manifold; d. andthence exits from the plenum.